Respiratory mask assembly

ABSTRACT

A flow regulation vent for venting washout gas to atmosphere and for regulating flow from a pressurized gas supply includes a fixed portion adapted to engage a gas supply conduit; a spring force biased movable portion structured for flowing communication with the pressurized gas supply; and a hinge pivotally connecting the movable portion to the fixed portion. The fixed portion has a gas flow orifice and the movable portion is pivotally movable between 1) a relaxed position, wherein below a specified operating pressure, the movable portion is pivoted by the spring force to a position away from the fixed portion to establish a first gas washout flow area between the movable portion and the gas flow orifice, and 2) a fully pressurized position. At or above the specified operating pressure, the pressurized gas offsets the spring force to pivot the movable portion to a position adjacent the fixed portion to cover at least a portion of the gas flow orifice and establish a second gas washout flow area between the movable portion and the gas flow orifice. The second gas washout flow area is less than the first gas washout flow area.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/322,237, filed Jan. 3, 2006, which is a continuation of U.S.application Ser. No. 10/164,370, filed Jun. 10, 2002, now U.S. Pat. No.7,207,334, which is a divisional of U.S. application Ser. No.09/498,705, filed Feb. 7, 2000, now U.S. Pat. No. 6,491,034, and relatedto the following applications: U.S. application Ser. No. 09/985,457,filed Nov. 2, 2001, now U.S. Pat. No. 7,185,652, and U.S. applicationSer. No. 09/985,458, filed Nov. 2, 2001, now U.S. Pat. No. 7,089,939,and U.S. application Ser. No. 11/285,077, now U.S. Pat. No. 7,174,893,each incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to improvements in patient gas deliveryapparatus of the kind used in the analysis and treatment of respiratorydisorders. The invention will be described with particular reference topatient gas delivery apparatus used in the treatment of respiratorydisorders such as Obstructive Sleep Apnea (OSA) but it is not intendedto be limited thereto.

The present invention also relates to an anti-asphyxia valve. The valvehas been developed primarily for use between a patient and means (e.g.,a blower or respirator) to deliver a breathable gas to the patient, suchas is used in the Continuous Positive Airway Pressure (CPAP) treatmentof Obstructive Sleep Apnea (OSA), and will be described hereinafter withreference to this application. The valve is also suitable for use inother gas delivery systems, such as those used in assisted respirationand Non-Invasive Positive Pressure Ventilation (NIPPV).

BACKGROUND OF THE INVENTION

Patient gas delivery apparatus of the kind having a mask worn by apatient and a gas delivery conduit attached to the mask are commonlyused in the analysis and treatment of respiratory disorders. The gasconduit delivers a gas under pressure to the patient. It is necessarythat the gas conduit is detachable from the mask to facilitate cleaning.

Patient gas delivery apparatus typically includes at a minimum, a gasdelivery conduit and a nose or full face mask. In some cases it is aclinical requirement that additional components be included, such asmeans for CO₂ washout, for example, vents, anti-asphyxia valves and thelike. In some cases, these additional components must be assembled inbetween the gas delivery conduit and the mask. Problems with prior artassemblies include: (a) they may be inadvertently assembled without theadditional components; (b) they may be incorrectly assembled, forexample, incorrectly aligned; (c) during the course of treatment, thepatient may inadvertently remove or dismantle the assembly andincorrectly reassemble it.

Further, known mask cushions are usually molded from a relatively soft,resilient, elastic material and they are shaped during manufacture tomatch the facial contours of an average intended wearer. However, aproblem with the known types of masks is that, because individuals varyso much from the average, the masks must be forced against theirinherent resiliency to deform and so adapt to the shapes of the users inorder to avoid gas leakage. This requires that the masks be securedfirmly by retaining straps or harnesses in order to prevent air leakage.

Flow generators are typically utilized to deliver a breathable gas(i.e., air) to a patient wearing the mask. In CPAP treatment, gas isdelivered to the patient's airways at about 2-30 cm H₂O aboveatmospheric pressure. The flow generator is generally connected toflexible tubing which is secured to the mask worn by the patient. If theflow generator's operation is interrupted as a result of a power outageor other mechanical or electrical failure, there may be a significantbuild up of carbon dioxide in the mask as the patient's exhaled air isnot washed out of outlet vents which are usually contained in the mask.This may present a health problem to the patient.

There have been numerous patents which have addressed some sort ofsafety valve for gas or air delivery masks. An example of such a patentis U.S. Pat. No. 5,438,981. This patent discloses a counter balanced,rigid valve element which depending on the gas flow, either covers anopening to the ambient air or covers the gas flow airway such that theair or breathing gas is forced out into the ambient air opening.However, this system suffers from being a fairly complicated andexpensive system whose correct operation relies on a counter balancedmoving part moving relative to its housing. Further, if any condensationfrom the air gets on or around the balanced valve element, the operationof this valve element can be compromised. This valve is also difficultto clean.

Applicant's International Application PCT/AU97/00849 discloses a valvehaving a single valve element. However, whilst being simpler thanpreceding valves of this type, the valve shown in PCT/AU97/00849 stillrelies on the use of a rigid valve element moving relative to itshousing and biased by magnets.

SUMMARY OF THE INVENTION

One aspect of the present invention is directed towards solving orameliorating one or more of these problems. One aspect of the inventionwill be described with reference to a full face mask and ananti-asphyxia valve, though other forms of mask and additionalcomponents may be used, such as the nasal mask shown in FIG. 4.

It is a further aspect of the present invention to provide an improvedvalve of simpler construction than those prior art valves discussedabove.

Accordingly, in a preferred embodiment, the present invention providesan anti-asphyxia valve adapted to, in use, be disposed between a patientand structure to deliver a breathable gas to the patient. The valveincludes a housing having an interior, at least one port to providefluid communication between the housing interior and atmosphere and atleast one flap comprising a first portion adapted for mounting to thehousing and a second portion adapted to flex between a first biased openposition allowing gas to pass from the housing interior through the atleast one port to atmosphere when a difference in gas pressure in thehousing interior and atmosphere is below a predetermined operatingthreshold and a second forced closed position substantially occludingthe at least one port when the difference in gas pressure between thehousing interior and atmosphere is substantially equal to or above theoperating threshold.

The operating threshold can be altered to suit particular applications.For example, a valve suitable for use in adult ventilatory assisttherapy has an operating threshold of about 2 cm H₂O.

The second portion preferably completely occludes the at least one portin the closed position.

Preferably, the housing may include two housing parts that arereleasably engageable with one another. In an embodiment, the housingparts engage by way of bayonet style fittings.

Desirably, the housing may include a gas inlet in the form of a firstsubstantially frusto-conical portion adapted to frictionally engage aflexible conduit in fluid communication with the structure to deliver abreathable gas to the patient and a gas outlet in the form of a secondsubstantially frusto-conical portion adapted to engage a mask or aflexible or rigid conduit in fluid communication with the mask. Thefrusto-conical portions preferably taper from a smaller distal end to alarger proximal end relative to the housing of the inlet valve.

Desirably also, one of the gas inlet or outlet may include asnap-engageable and detachable swivel portion adapted to engage the maskor flexible conduit. In a preferred embodiment, the inlet and outlet arerespectively provided on one of the two housing parts.

In an embodiment, the housing may include a plurality of ports spacedabout the periphery thereof and the second portion of the flap includesa like plurality of flaps. In one preferred form, the housing includessix ports (three pairs of ports) and the second portion of the flapincludes three flaps each adapted to close adjacent pairs of the ports.In another embodiment, the second portion of the flap is a single flapwhich is adapted to occlude all the ports in the second position. Thesingle flap can also include perforations, ribs, pleats or folds or thelike.

In one form, the first and second portions are integrally formed. Inanother form, the first and second portions are initially formed fromseparate components that are later attached to each other.

The first portion preferably includes a rim adapted to assist inmounting the flap means to the housing. In an embodiment, the rim is anexternal rim of rectangular cross section which is adapted to engage aninternal recess of substantially like cross-section in the housing.

The first portion may also include a cylindrical portion between the rimand the second portion.

The rim and/or the cylindrical portion may also be tapered.

The second portion of the flap preferably terminates in an internalorifice. In a preferred embodiment, the orifice can include a one-wayvalve adapted to only allow gas flow through the orifice in a directiontowards the patient.

In one preferred form, the flap is substantially round in cross-section.In other forms, the cross-section of the flap is full or part ellipticalor rectangular or other non-round shapes.

The housing is preferably manufactured from plastics material, forexample polycarbonate. The flap assembly is preferably manufactured froma flexible elastomeric material such as a silicone rubber.

In another embodiment, the valve is integral with a mask.

In a further embodiment, the housing is of unitary construction.

These and other aspects of the invention will be described in orapparent from the following detailed description of preferredembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Further preferred embodiments of the invention will now be described byway of example only with reference to the accompanying drawings inwhich:

FIG. 1 is a perspective view showing the mask, anti-asphyxia valvehousing and conduit connection assembly;

FIG. 2 is an exploded view of the anti-asphyxia valve and conduitconnection assembly shown in FIG. 1;

FIG. 3 is an exploded view of the mask assembly shown in FIG. 1;

FIG. 4 is a general schematic drawing of a system comprising a flowgenerator being connected to a valve and mask via tubing in which themask is connected to a patient;

FIG. 5 is a side view of an embodiment of a valve of the presentinvention;

FIG. 6A is a cross-sectional view of FIG. 5 in which the flow generatoris not operating;

FIG. 6B is a cross-sectional view of FIG. 5 in which the flow generatoris operating and generating a pressure differential below the operatingthreshold;

FIG. 7 is a cross-sectional view of the valve of FIG. 5 in which theflow generator is operating and generating a pressure differential abovethe operating threshold;

FIG. 8 is a perspective view of an alternative embodiment of the presentinvention wherein the valve is attached to a mask having a CO₂ gaswashout vent;

FIG. 9 is a cross-sectional view of a further embodiment of the presentinvention wherein the valve has a unitary housing;

FIG. 10 is a cross-sectional view of a yet further embodiment of thepresent invention wherein the valve includes a swivel conduit connector;

FIG. 11 is a perspective view of another embodiment of the presentinvention wherein the valve is integral with a mask;

FIG. 12 is a cross-sectional view of an embodiment of a flap;

FIG. 13 is a cross-sectional view of another embodiment of a flap;

FIG. 14 is a cross-sectional view of yet another embodiment of a flap;

FIG. 15 is a perspective view of a further embodiment of a flap;

FIG. 16 is a perspective view of a further embodiment of a flap;

FIG. 17 is a perspective view of a further embodiment of a flap;

FIG. 18 is a perspective view of a further embodiment of a flap;

FIG. 19 is a perspective view of the flap shown in FIG. 14;

FIG. 20 is a perspective view of a further embodiment of a flap;

FIG. 21 is a half-cutaway view of the flap shown in FIG. 20;

FIG. 22 is a first sectional view of the flap of FIG. 20 along the line22, 23-22, 23;

FIG. 23 is a second sectional view of the flap of FIG. 20 along the line22, 23-22, 23;

FIG. 24 is a sectional view of the flap means of FIG. 20 along the line24-24;

FIG. 25 is a perspective view of a further embodiment of a flap;

FIG. 26 is a cross-sectional side view of the flap of FIG. 25 in theopen position; and

FIG. 27 is a cross-sectional side view of the flap of FIG. 25 in theclosed position.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1 a mask frame is shown generally at 10. The mask is designed tobe worn on a patient's face and is secured by means of straps (notshown) received by attachment points 18.

A conduit end assembly is shown generally at 20, including an elbow part26 having at one end thereof a combined vent/connector piece 28. Theelbow and vent/connector piece together form a housing for ananti-asphyxia valve (as will be further discussed) or other internalcomponents (not shown). At the other end of the elbow is a detachableswivel tube 29 for connection of the gas delivery conduit (not shown).

The mask 10 includes a circular aperture 12 sized to receive a matingportion 22 of the vent/connector piece 28. The mating portion 22 has anannular groove 23 formed therein that receives a locking means 30 in theform of a C-shaped clip attached after mating to the mask. The clip 30has an outside diameter greater than the width of the aperture 12 and aninner diameter adapted to ensure a snug fit within the annular groove23. The clip 30 is resilient and can expand sufficiently to allow theclip to be fitted into and removed from the groove 23. As shown in FIG.1, the clip 30 is located onto the mating portion 22 on the inside ofthe mask 10. In this position, the clip 30 is inaccessible while themask is being worn by a patient. Once the mating portion 22 of thevent/connector piece 28 has been inserted through the aperture 12 andthe locking clip placed in the annular groove, the conduit end assembly20 and the mask 10 cannot be separated without first removing the maskfrom the patient.

An exploded view of one embodiment of the anti-asphyxia valve andconduit connector assembly is shown in FIG. 2.

As illustrated in FIG. 2, the end of the elbow 26 adjacent the mask 10is fitted with an anti-asphyxia valve arrangement that provides an airpassage to the patient in the event of failure of the gas deliveryapparatus, consisting of a valve membrane 27 fitted into the end ofelbow 26 and vents 31 in the vent/connector piece 28. During properoperation of the gas delivery system, the valve membrane remains in theorientation shown in FIG. 2, closing off the vents 31. In the event of adrop in pressure below a predetermined level, the valve membrane 27flips to a reverse orientation, opening the vents 31. The constructionand operation of the anti-asphyxia valve is described in more detail inthe Applicant's Australian Patent Application No. 65527/99, the contentsof which are incorporated herein by reference and described herein.

Resilient detents 42 on the elbow 26 pass through and engage behindslot-forming formations 44 in the vent/connector piece 28 to providereleasable engagement of the two parts.

The vent/connector piece has a collar 47 that abuts a correspondingsurface of the mask 10 to limit the distance that the vent/connectorpiece can be inserted into the mask aperture 12 (FIG. 1). Thecorresponding surface is an annulus 50 having a protruding rim 51 theouter circumference of which preferably engages the inner surface of thedetents 42 on insertion of the mating portion 22 into the aperture 12.This engagement prevents the detents from being pushed radially inwardssufficiently for the detents to disengage from behind the slot-formingformations 44, thus preventing the elbow 26 and vent/connector piece 28from separating whilst still attached to the mask frame 11, for exampleduring patient treatment. The result of this is that the anti-asphyxiavalve arrangement cannot be disassembled without first removing theelbow and vent/connector piece assembly from the mask. However, oncedisconnected from the mask, the assembly may be readily separated forcleaning and then reassembled.

The other, distal end of elbow 26 has an enlarged diameter portion whichreceives the swivel tube 29, onto which a flexible gas conduit (notshown) may be fitted. The swivel tube 29 has a pair of flanges 56 and 57defining an annular groove 58 therebetween. The end of swivel tube 29 isinserted into the elbow 26 until the end flange 57 abuts an innersurface (not shown) within elbow 26. In this position the annular groove58 is at least partially aligned with an annular groove 61 in theexterior of the elbow, which receives a swivel clip 41.

The swivel clip 41 has an inner diameter only slightly greater than thediameter of the groove 61, to ensure a snug fit within the groove. Theclip 41 is resilient to permit sufficient expansion for attachment andremoval of the clip from the groove. The groove 61 has slots 59 whichreceive lugs 62 on the clip. These lugs rotatably engage in the groove58 between flanges 56 and 57 of the swivel tube. The swivel tubearrangement thus acts as a rotatable coupling between the conduit andthe elbow whilst allowing quick attachment and removal of the gasconduit from the elbow regardless of whether the assembly is attached tothe mask at the time.

As shown in FIG. 3, the mask includes a mask frame 11, cushion 13 andcushion clip 14. The cushion is received on a rib 15 extending aroundthe periphery of the mask frame 11. The cushion is held to the rib bythe cushion clip 14. The mask frame includes attachment points 18 thatreceive straps (not shown) for attaching the mask to the patient, anaperture 16 for receiving an air vent 17, and measurement ports 19.

The details of construction and of the operation of the anti-asphyxiavalve will now be described with reference to FIGS. 4 27. As illustratedin FIG. 4, a flow generator 100 having a flexible air flow conduit 112is secured to an embodiment of a valve 114 which is thereafter connectedto a nasal mask 116 of a patient 121. The mask 116 illustrated in FIG. 4includes a mask cushion 117 and a CO.sub.2 gas washout vent 119 and isjust one example of numerous types of patient interface. As describedabove, the mask may be designed to cover the patient's face.

The location of the valve 114 shown in FIG. 4 is just one example ofnumerous possible locations. The valve 114 could be connected to themask 116 as shown in FIGS. 4 and 8, or it could be an integral part ofthe mask 116, as shown in FIG. 11. There could also be two or morevalves located on a single system. It is preferred to put the valve 114as close to the mask 116 as possible, or to make it part of the mask116.

The flow generator 100 produces a flow of breathable gas, typically air,and can be an electric blower, a controlled bottled gas system, aventilator, or any other type of device that delivers breathable,therapeutic or anaesthetic gas.

The valve 114 shown in FIGS. 4 to 7 is comprised of two housing parts118 and 120 which may be locked together by way of respective male andfemale bayonet fittings 122 and 124. The housing part 118 includes aninlet in the form of frusto-conical portion 126. The housing part 120includes an outlet in the form of frusto-conical portion 128. Theportions 126 and 128 allow push-on assembly and frictional engagementwith the gas supply conduit 112 and the mask housing 116 respectively.The housing part 120 includes six peripherally arranged ports 130 eachseparated by one of six connecting members 131. A flexible flap 132 ofgenerally round cross-section is formed from a silicone rubber and has acentral orifice 133. The flap 132 includes a first portion in the formof outer rim 134. The flap 132 is glued, clamped or otherwise attachedor mounted to the second housing part 120 at the outer rim 134. The flap132 includes a second portion in the form of flexible flaps 135.

As shown in FIG. 6A, when the difference in the gas pressure between thehousing interior and atmosphere is below a predetermined operatingthreshold of, for example 2 cm H₂O, the flaps 135 are in a relaxed stateand inherently biased to an “open” position allowing gas flow from theinterior of the housing through the ports 130 and to atmosphere.Accordingly, if the supply of breathable gas falls below the thresholdor ceases, the patient 121 is still able to inhale air through the openports 130 and exhale carbon dioxide out through the open ports 130, asindicated by arrows 129.

When the breathable gas supply commences or resumes and the differencein the gas pressure between the housing interior and atmosphere buildsup to equal or above 2 cm H₂O the flaps 135 move to a “closed” positionoccluding the ports 130 shown in FIG. 7. Thereafter the flaps 135 aremaintained closed by the gas pressure in the housing interior beingabove the predetermined operating threshold. In this closed position allthe gas supplied from the flow generator 100 can pass through theorifice 133 of the flap 132 to be delivered to the mask 116 of thepatient 121, as indicated by arrows 139.

In the embodiment shown in FIGS. 4 to 7, the flap 132 has three of theflaps 135 which each subtend an angle of approximately 120°. The threeflaps 135 are each separated by slits 136 (only one of three slits 136shown). The slits 136 allow the flaps 135 to flex between the open andclosed positions, as shown in FIG. 6A and FIG. 7 respectively, withoutcrinkling or binding. Every second one of the six connecting members 131includes a flange 137 which abuts adjacent outer edges (adjacent theslits 136) of each of the flaps 135 in the closed position to assist insealing the ports 130.

Each flap 132 is preferably manufactured by moulding of a singlesilicone rubber component in the shape shown in FIG. 6A (i.e. the openposition). The flaps 135 are preferably 0.15 mm thick. The thickness ofeach of the flaps is adjusted to suit their application and, inparticular, the pressure of the operating threshold. If too flimsy, theflaps will distend or crumple across the ports 130 and may not move toreturn from the closed position at the correct pressure. If too stiff,the flaps will not move to the closed position at the correct pressure.

Testing of a prototype of the valve 114 shown in FIGS. 4 to 7 wasconducted with a flow generator connected to the inlet cylindricalportion 126 via an air flow conduit. A mask was connected to the valve114 at the outlet cylindrical portion 128. The mask cushion seals themask interior relative to the wearer's face such that the only gas flowfrom the mask 116 to atmosphere is through the mask gas washout vent.

With this arrangement the flap assembly 132 closed the ports 130 at anapproximately 2 cm H₂O pressure difference (operating threshold) betweenthe interior of the valve 114 and atmosphere.

The inherent resilience of the silicone rubber flaps 135 re-opened theports 130 when the pressure difference (operating threshold) between theinterior of the valve 114 and atmosphere fell below approximately 2 cmH₂O.

FIG. 6B shows the flap assembly 132 in the open position when the flowgenerator is operating but the pressure difference between the valveinterior and atmosphere is below the operating threshold. Under theseconditions, some of the supplied gas passes through the ports 130 andthe remainder passes through the valve outlet 128 to the mask, asindicated by arrows 127 and 139 respectively.

As the flow through the valve outlet 128 is thus less than the suppliedflow through the valve inlet 126, a pressure differential is createdbetween the downstream side of the flaps 135 (that side adjacent thevalve outlet 128) and the upstream side of the flaps 135 (that sideadjacent the valve inlet 126) which forces the flaps 135 to deformagainst their inherent resilience towards the ports 130 and, ultimately,to the closed position shown in FIG. 7.

When in the closed position shown in FIG. 7, there is no gas flowthrough the ports 130. Under these conditions, a pressure differentialbetween the valve interior and atmosphere above the operating thresholdwill maintain the flaps 135 in the closed position.

The inherent resilience of the flaps 135 moves the flaps 135 away fromthe ports 130 and towards the open position when the pressure differencebetween the valve interior and atmosphere falls below the operatingthreshold.

FIG. 8 illustrates another embodiment in which the valve 114 is attachedto another type of mask 116 that includes a CO₂ gas washout vent 138.

FIG. 9 illustrates an embodiment of the valve 114 having a unitaryhousing 140.

FIG. 10 illustrates another embodiment of the valve 114 having a unitaryhousing 140 and a swivel connector 142 that snap-engages with thecylindrical portion 128 over resilient fingers 144. This embodimentobviates the need for a separate swivel connector elsewhere in the gassupply circuit.

In another embodiment (not shown) the swivel connection 142 is used inconjunction with the unitary housing 140.

FIG. 11 illustrates a further embodiment of the valve 114 incorporatedinto a mask 146 having a mask shell 148 and a mask cushion 150. In thisembodiment, the valve 114 is integrally formed with the mask shell 148thereby obviating the push-on connection between the mask 116 and thevalve 114.

FIG. 12 shows an embodiment of the flap 132 which includes an externalrim 152 of stepped cross section which assists in locating the flap 132in the housing. The rim 154 is received within a corresponding recess inthe housing to facilitate locating and mounting the flap 132 in thehousing.

FIG. 13 shows another embodiment of the flap 132 having an internal rim154 of rectangular cross section.

FIGS. 14 and 19 show yet another embodiment of the flap means 132 havinga substantially cylindrical formation 156 between the flaps 135 and therim 152. The cylindrical formation 156 and the rim 152 facilitatelocating the flap 132 with correct orientation in the housing.

FIG. 15 illustrates a further embodiment of the flap 132 which includesa series of pleats or folds 160 which flex to allow movement of the flap132 between the open and closed positions.

FIG. 16 shows another embodiment of the flap 132 similar to that shownin FIG. 14 but without the slits 136. This embodiment thus has only asingle flap 135 which distorts when moving between the open and closedpositions.

FIG. 17 shows an embodiment similar to that of FIG. 16 but includingthree rows of perforations 158 which provide localised flexibility toassist in movement of the flaps 135 between the open and closedpositions.

FIG. 18 shows an embodiment of a flap 132 that has the cylindricalformation 156 of the embodiment of FIGS. 14 and 19 and the pleats orfolds 160 of the embodiment of FIG. 15.

FIGS. 20 and 21 show a further embodiment of a flap 132 with a singleflap 135 that includes a number of radial protuberances' or ribs 162 ofgreater thickness than the flap 135. In the embodiment shown, the ribs162 are of equal thickness. In other embodiments (not shown) the ribsare of unequal thickness and, for example, can be thicker on one sidefor operation in applications where flow is different across the flapsuch as in a curved or angled conduit or the like.

FIGS. 22 and 23 show examples of the cross section the flap 135 canassume in the closed position.

FIG. 24 shows an example of the cross section that the ribs 162 canassume in the open position.

FIGS. 25 and 27 are schematic views of another embodiment of a flap 132that includes a one-way valve device 164 adapted to only allow gas flowin the direction of the patient. The one-way valve device 164 is knownas a non-rebreathe valve.

FIGS. 25 and 27 show the flap 132 in the closed position and the one-wayvalve 164 in the open position, thereby allowing gas flow to thepatient, as indicated by arrows 166. FIG. 26 shows the flap 132 in theopen position and the one-way valve 164 in the closed position, therebydirecting all of the gas flow directed through the ports of the valve toatmosphere.

Another embodiment of the invention (not shown) includes a port orseries of ports that function as both the flap assembly ports and themask CO₂ gas washout port.

In this embodiment, the ports and the flap assembly are sized so eachport is not totally occluded by the flap assembly in the closedposition. Accordingly, in the closed position each port is occluded toan extent that it is of a size suitable to function as the mask CO₂ gaswashout vent. When the pressure differential between the interior of thevalve and atmosphere is below the operational threshold, the flapassembly moves to the open position and each port to atmosphere isenlarged to a size suitable to function as the anti-asphyxia port.

One advantage is that the valve can be used with nasal, mouth mask andfull face (nose and mouth) mask systems for both adults and infants. Inthe situation of infants, the airflow is generally less, and thus theforce needed to flex the flap assembly into the closed position islowered accordingly.

The valve according to the present invention can be used for any type ofair delivery system, it is preferably used in CPAP applications for thetreatment of OSA or NIPPV.

Preferred embodiments of the valve of the present invention have theadvantage of being able to operate independent of orientation. That is,although the valve has to be connected in the right direction betweenthe flow generator and the mask, it can be inverted, held sideways, etc.which often occurs during the time when the patient sleeps.

Another advantage of the valve of the present invention is it may haveonly one moving or flexing part providing consistent operation.

Further, the valve can be disassembled, cleaned and reassembled veryeasily at home or at a hospital or clinic due to it having less parts.

The valve of the present invention is also very quiet in operation.

While particular embodiments of this invention have been described, itwill be evident to those skilled in the art that the present inventionmay be embodied in other specific forms without departing from theessential characteristics thereof. The present embodiments and examplesare therefore to be considered in all respects as illustrative and notrestrictive, the scope of the invention being indicated by the appendedclaims rather than the foregoing description, and all changes which comewithin the meaning and range of equivalency of the claims are thereforeintended to be embraced therein.

1. A flow regulation vent for venting washout gas to atmosphere and forregulating flow from a pressurized gas supply, comprising: a fixedportion adapted to engage a gas supply conduit; a spring force biasedmovable portion structured for flowing communication with thepressurized gas supply; and a hinge pivotally connecting the movableportion to the fixed portion; wherein the fixed portion has a gas floworifice and the movable portion is pivotally movable between 1) arelaxed position, wherein below a specified operating pressure, themovable portion is pivoted by the spring force to a position away fromthe fixed portion to establish a first gas washout flow area between themovable portion and the gas flow orifice, and 2) a fully pressurizedposition, wherein at or above the specified operating pressure, thepressurized gas offsets the spring force to pivot the movable portion toa position adjacent the fixed portion to cover at least a portion of thegas flow orifice and establish a second gas washout flow area betweenthe movable portion and the gas flow orifice, wherein the second gaswashout flow area is less than the first gas washout flow area.
 2. Aflow regulation vent according to claim 1, wherein the fixed portion andthe movable portion are unitarily formed from a single piece ofmaterial.
 3. A flow regulation vent according to claim 1, wherein themovable portion further comprises at least one bleed orificetherethrough to provide a minimum bleed flow through the vent even whenthe movable portion is in the fully pressurized position.
 4. A flowregulation vent according to claim 1, wherein the fixed portion furthercomprises at least one bleed orifice therethrough to provide a minimumbleed flow through the vent even when the movable portion is in thefully pressurized position.
 5. A flow regulation vent according to claim1, further comprising a base adapted to be positioned between the gassupply conduit and the flow regulation vent, the base having at leastone orifice therethrough to provide gas communication between the gassupply conduit and the flow regulation vent, the base also having atleast one supporting surface for supporting a periphery of the fixedportion.
 6. A flow regulation vent according to claim 5, furthercomprising a cover adapted to engage the base and fix the flowregulation vent therebetween, the cover having at least one orificetherethrough for providing gas communication between the flow regulationvent and the atmosphere.
 7. A flow regulation vent according to claim 1,wherein the hinge provides at least a portion of the spring force.
 8. Amask for supplying breathable gas pressurized above atmospheric pressureto a human, the mask comprising: a shell adapted to cover at least oneof the human's mouth and the human's nostrils; a gas supply conduitflowingly connected to the shell and adapted to be connected to apressurized gas supply; and a flow regulation vent comprising a fixedportion adapted to be connected to one of the shell and the gas supplyconduit; a spring force biased movable portion adapted to be flowinglyconnected to the pressurized gas supply; and a hinge pivotallyconnecting the movable portion to the fixed portion; wherein the fixedportion has a gas flow orifice and the movable portion is pivotallymovable between 1) a relaxed position, wherein below a specifiedoperating pressure, the movable portion is pivoted by the spring forceto a position away from the fixed portion to establish a first gaswashout flow area between the movable portion and the gas flow orifice,and 2) a fully pressurized position, wherein at or above the specifiedoperating pressure, the pressurized gas offsets the spring force topivot the movable portion to a position adjacent the fixed portion tocover at least a portion of the gas flow orifice and establish a secondgas washout flow area between the movable portion and the gas floworifice, wherein the second gas washout flow areas is less than thefirst gas washout flow area.
 9. A mask according to claim 8, wherein thefixed portion and the movable portion are unitarily formed from a singlepiece of material.
 10. A mask according to claim 8, wherein the movableportion further comprises at least one bleed orifice therethrough toprovide a minimum bleed flow through the vent even when the movableportion is in the fully pressurized position.
 11. A mask according toclaim 8, wherein the fixed portion further comprises at least one bleedorifice there through to provide a minimum bleed flow through the venteven when the movable portion is in the fully pressurized position. 12.A mask according to claim 8, further comprising a cover adapted toengage the one of the shell and the gas supply conduit and fix the flowregulation vent therebetween, the cover having at least one orificetherethrough for providing gas communication between the flow regulationvent and the atmosphere.
 13. A mask according to claim 8, wherein thehinge provides at least a portion of the spring force.
 14. A mask forsupplying breathable gas pressurized above atmospheric pressure to ahuman, the mask comprising: a shell adapted to cover at least one of thehuman's mouth and the human's nostrils; a gas supply conduit flowinglyconnected to the shell and adapted to be connected to a pressurized gassupply; and a flow regulation vent comprising a fixed portion adapted tobe connected to one of the shell and the gas supply conduit; a springforce biased movable portion adapted to be flowingly connected to thepressurized gas supply; and a hinge pivotally connecting the movableportion to the fixed portion, the fixed portion, the movable portion andthe hinge being unitarily formed from a single sheet of material;wherein the fixed portion has a gas flow orifice and the movable portionis pivotally movable between 1) a relaxed position, wherein below aspecified operating pressure, the movable portion is pivoted by thespring force to a position away from the fixed portion to establish afirst gas washout flow area between the movable portion and the gas floworifice, and 2) a fully pressurized position, wherein at or above thespecified operating pressure, the pressurized gas offsets the springforce to pivot the movable portion to a position adjacent the fixedportion to cover at least a portion of the gas flow orifice andestablish a second gas washout flow area between the movable portion andthe gas flow orifice, wherein the second gas washout flow area is lessthan the first gas washout flow area.
 15. In a chamber containing a gasand having an interior pressurized to a first pressure and an exteriorpressurized to a second pressure, a valve for regulating a flow of airthrough an orifice, the valve having a spring force biased movableportion pivotably connected to a fixed portion to create a gas washoutflow area between the movable portion and the orifice, wherein themoveable portion is pivotably movable between: (i) a relaxed position,wherein the gas washout flow area has a first value; and (ii) a secondposition, wherein when the first pressure is at a specified operatingpressure, the pressure difference between the first and second pressuresoffsets the spring force to pivot the movable portion to a positionadjacent the fixed portion to cover at least a portion of the orificesuch that the gas washout flow area has a second value less than thefirst value.
 16. In a chamber containing a gas and having an interiorpressurized to a first pressure and an exterior pressurized to a secondpressure, a valve for regulating a flow of air through an orifice, thevalve having a resiliently bendable cantilever flap to create a gaswashout flow area between the cantilever flap and the orifice, whereinthe cantilever flap is bendable between: (i) a relaxed position, whereinthe gas washout flow area has a first value; and (ii) a second position,wherein when the first pressure is at a specified operating pressure,the pressure difference between the first and second pressures offsetsthe flap resilience to bend the flap to a position adjacent the fixedportion to cover at least a portion of the orifice such that the gaswashout flow area has a second value less than the first value.